Jerry Hey wrote:

It is time for me to decide on the drive ratios for my chain psru.
Basically, if I want to avoid special orders (and considerable expense)I
have two choices. 2:1 or 2.21:1.  The 2:1 would have max cruise (prop at
2750) at 5500 eng . rpm.  The 2.21:1 would achieve the same at  6077
rpm.   Of course, the engine would be making more power in the latter
case.  With the extra power, comes additional heat generation.  I think
the guys who want to run the 2.8 gear box at over 7000 rpm may face
formitible  cooling issues.  A lot of radiator core and a lot of air
will be required and that adds up to a lot of drag.  May be  sound and
fury signifying nothing as far as practical, high speed cruising is
concerned.   But that is beside the point of this note which is my

drive.

It seems to me  the 2.21 ratio would be just about perfect.  But I have
never heard of any one claim that they could actually cruise at 6000
rpm.  Even the planes in the Everett Hatch RACE, ran less than 6000 rpm,
I believe.

I would like to think it would be possible to set the throttle at 6077
rpm and just leave it there.

The Star Mazdas operate in this RPM range ( 6000 to 6800) and seem to
survive very well.

I will appreciate anyone's commentary.    Jerry

Jerry
 My 2.85 system will run all day at 6400rpm 180 MPH coolant sitting on the

thermostat. RV6A standard air inlet and 7" X 2 1/2" inlet for oil. Extra
oulets at the side which need adjustable flaps. I intend to have max RPM at
7200 when I get the inlet to the engine and prop. pitch sorted. I will let
you know when it goes faster than You Know Who.
Ian

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